Improved synthesis for the rodenticides, diphenacoum and brodifacoum

Abstract

An improved synthesis of the 3-[3-(p-substituted phenyl)-1,2,3,4-tetrahydro-1-napththyl]-4-hydroxycoumarins, diphenacoum and brodifacoum, is described. The process is primarily based on the formation of one of the crucial bonds in the carbon backbone using organocopper methodology, and on the coupling of the 4-hydroxycoumarin moiety to the 3-biphenyl tetralin unit under strongly acidic conditions.